Transition period for image transitions in a media file

ABSTRACT

Systems, methods and apparatus for processing image data are described. One example method includes performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of pictures according to a media file format, and the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format. The media file format specifies a suggested transition period of an image item to be applied for a transition between the image item and a next image item during displaying of the pictures as a slideshow.

CROSS REFERENCE TO RELATED APPLICATIONS

Under the applicable patent law and/or rules pursuant to the Paris Convention, this application is made to timely claims the priority to and benefits of U.S. Provisional Patent Application No. 63/073,829, filed on Sep. 2, 2020, and U.S. Provisional Patent Application No. 63/087,458, filed on Oct. 5, 2020. For all purposes under the law, the entire disclosures of the aforementioned applications are incorporated by reference as part of the disclosure of this application.

TECHNICAL FIELD

This patent document relates to image and video coding and decoding.

BACKGROUND

Digital video accounts for the largest bandwidth use on the internet and other digital communication networks. As the number of connected user devices capable of receiving and displaying video increases, it is expected that the bandwidth demand for digital video usage will continue to grow.

SUMMARY

The present document discloses techniques that can be used by video encoders and decoders for processing coded representation of a video or an image according to a file format.

In one example aspect, a method for processing image data is disclosed. The method includes performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of pictures according to a media file format, and the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format. The media file format specifies a suggested transition period of an image item to be applied for a transition between the image item and a next image item during displaying of the pictures as a slideshow.

In another example aspect, a method for processing image data is disclosed. The method includes performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of pictures according to a media file format, and the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format. The media file format specifies that multiple transition effects are allowable for a transition to be applied between displaying of a first image item and a second image item as a slideshow.

In another example aspect, a method for processing image data is disclosed. The method includes performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of one or more pictures according to a media file format, and the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format. The video coding format defines multiple profiles. The media file format specifies that the bitstream is represented in a file having a specific brand, and the media file format further specifies that one or more profiles used for representing the video in the bitstream are agnostic of the specific brand.

In another example aspect, a method for processing image data is disclosed. The method includes performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of one or more pictures according to a media file format, and the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format. The media file format specifies one or more file brands or one or more image item types associated with the video coding format. The media file format specifies that the bitstream that conforms to one of the one or more file brands or one of the one or more image item types includes a single access unit, and the single access unit includes a single picture that is at least partially intra-coded.

In another example aspect, a method for processing image data is disclosed. The method includes performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of pictures according to a media file format. The bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format. The media file format specifies that an operating point information (OPI) network abstraction layer (NAL) unit is absent in an image item or samples of the image item having a specific image item type.

In one example aspect, a video processing method is disclosed. The method includes performing a conversion between a visual media comprising a sequence of one or more images and a bitstream representation according to a file format; wherein the file format is configured to include one or more syntax element indicating a transition property between the one or more images during displaying of the one or more images.

In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a visual media comprising a sequence of one or more images and a bitstream representation according to a file format; wherein the file format specifies that, in case that the visual media is represented in a file having a specific file brand, the file format is restricted according a rule.

In another example aspect, another video processing method is disclosed. The method includes performing a conversion between a visual media comprising a sequence of one or more images and a bitstream representation according to a file format; wherein the file format is configured to indicate an image type for the one or more images according to a rule.

In yet another example aspect, a video encoder apparatus is disclosed. The video encoder comprises a processor configured to implement above-described methods.

In yet another example aspect, a video decoder apparatus is disclosed. The video decoder comprises a processor configured to implement above-described methods.

In yet another example aspect, a computer readable medium having code stored thereon is disclose. The code embodies one of the methods described herein in the form of processor-executable code.

In yet another example aspect, a computer readable medium having a bitstream stored thereon is disclosed. The bitstream is generated using a method described in the present document.

These, and other, features are described throughout the present document.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of an example video processing system.

FIG. 2 is a block diagram of a video processing apparatus.

FIG. 3 is a flowchart for an example method of video processing.

FIG. 4 is a block diagram that illustrates a video coding system in accordance with some embodiments of the present disclosure.

FIG. 5 is a block diagram that illustrates an encoder in accordance with some embodiments of the present disclosure.

FIG. 6 is a block diagram that illustrates a decoder in accordance with some embodiments of the present disclosure.

FIG. 7 shows an example of encoder block diagram.

FIG. 8 is a flowchart representation of a method for processing image data in accordance with one or more embodiments of the present technology.

FIG. 9 is a flowchart representation of a method for processing image data in accordance with one or more embodiments of the present technology.

FIG. 10 is a flowchart representation of a method for processing image data in accordance with one or more embodiments of the present technology.

FIG. 11 is a flowchart representation of a method for processing image data in accordance with one or more embodiments of the present technology.

FIG. 12 is a flowchart representation of a method for processing image data in accordance with one or more embodiments of the present technology.

DETAILED DESCRIPTION

Section headings are used in the present document for ease of understanding and do not limit the applicability of techniques and embodiments disclosed in each section only to that section. Furthermore, H.266 terminology is used in some description only for ease of understanding and not for limiting scope of the disclosed techniques. As such, the techniques described herein are applicable to other video codec protocols and designs also. In the present document, editing changes are shown to text by strikethrough indicating cancelled text and highlight indicating added text (including boldface italic), with respect to the current draft of the VVC specification.

1. Overview

This document is related to image file format. Specifically, it is related to signalling and storage of images and image transitions in a media file based on the ISO base media file format. The ideas may be applied individually or in various combination, for images coded by any codec, e.g., the Versatile Video Coding (VVC) standard, and for any image file format, e.g., the VVC image file format being developed.

2. Abbreviations

-   -   AU Access Unit     -   AUD Access Unit Delimiter     -   AVC Advanced Video Coding     -   BP Buffering Period     -   CLVS Coded Layer Video Sequence     -   CLVSS Coded Layer Video Sequence Start     -   CPB Coded Picture Buffer     -   CRA Clean Random Access     -   CTU Coding Tree Unit     -   CVS Coded Video Sequence     -   DCI Decoding Capability Information     -   DPB Decoded Picture Buffer     -   DUI Decoding Unit Information     -   EOB End Of Bitstream     -   EOS End Of Sequence     -   GDR Gradual Decoding Refresh     -   HEVC High Efficiency Video Coding     -   HRD Hypothetical Reference Decoder     -   IDR Instantaneous Decoding Refresh     -   ILP Inter-Layer Prediction     -   ILRP Inter-Layer Reference Picture     -   IRAP Intra Random Access Picture     -   JEM Joint Exploration Model     -   LTRP Long-Term Reference Picture     -   MCTS Motion-Constrained Tile Sets     -   NAL Network Abstraction Layer     -   OLS Output Layer Set     -   PH Picture Header     -   POC Picture Order Count     -   PPS Picture Parameter Set     -   PT Picture Timing     -   PTL Profile, Tier and Level     -   PU Picture Unit     -   RAP Random Access Point     -   RBSP Raw Byte Sequence Payload     -   SEI Supplemental Enhancement Information     -   SLI Subpicture Level Information     -   SPS Sequence Parameter Set     -   STRP Short-Term Reference Picture     -   SVC Scalable Video Coding     -   VCL Video Coding Layer     -   VPS Video Parameter Set     -   VTM VVC Test Model     -   VUI Video Usability Information     -   VVC Versatile Video Coding

3. Initial Discussion 3.1. Video Coding Standards

Video coding standards have evolved primarily through the development of the well-known ITU-T and ISO/IEC standards. The ITU-T produced H.261 and H.263, ISO/IEC produced MPEG-1 and MPEG-4 Visual, and the two organizations jointly produced the H.262/MPEG-2 Video and H.264/MPEG-4 Advanced Video Coding (AVC) and H.265/HEVC standards. Since H.262, the video coding standards are based on the hybrid video coding structure wherein temporal prediction plus transform coding are utilized. To explore the future video coding technologies beyond HEVC, the Joint Video Exploration Team (JVET) was founded by VCEG and MPEG jointly in 2015. Since then, many new methods have been adopted by JVET and put into the reference software named Joint Exploration Model (JEM). The JVET was later renamed to be the Joint Video Experts Team (JVET) when the Versatile Video Coding (VVC) project officially started. VVC is the new coding standard, targeting at 50% bitrate reduction as compared to HEVC, that has been finalized by the JVET at its 19th meeting ended at Jul. 1, 2020.

The Versatile Video Coding (VVC) standard (ITU-T H.266|ISO/IEC 23090-3) and the associated Versatile Supplemental Enhancement Information (VSEI) standard (ITU-T H.274|ISO/IEC 23002-7) have been designed for use in a maximally broad range of applications, including both the traditional uses such as television broadcast, video conferencing, or playback from storage media, and also newer and more advanced use cases such as adaptive bit rate streaming, video region extraction, composition and merging of content from multiple coded video bitstreams, multiview video, scalable layered coding, and viewport-adaptive 360° immersive media.

3.2. File Format Standards

Media streaming applications are typically based on the IP, TCP, and HTTP transport methods, and typically rely on a file format such as the ISO base media file format (ISOBMFF). One such streaming system is dynamic adaptive streaming over HTTP (DASH). For using a video format with ISOBMFF and DASH, a file format specification specific to the video format, such as the AVC file format and the HEVC file format, would be needed for encapsulation of the video content in ISOBMFF tracks and in DASH representations and segments. Important information about the video bitstreams, e.g., the profile, tier, and level, and many others, would need to be exposed as file format level metadata and/or DASH media presentation description (MPD) for content selection purposes, e.g., for selection of appropriate media segments both for initialization at the beginning of a streaming session and for stream adaptation during the streaming session.

Similarly, for using an image format with ISOBMFF, a file format specification specific to the image format, such as the AVC image file format and the HEVC image file format, can be needed.

3.3. VVC Video File Format

The VVC video file format, the file format for storage of VVC video content based on ISOBMFF, is currently being developed by MPEG.

3.4. VVC Image File Format and Image Transitions

The VVC image file format, the file format for storage of image content coded using VVC, based on ISOBMFF, is currently being developed by MPEG.

In some cases, a design for slideshow signaling is included, with the support of image transition effects such as wipe, zoom, fade, split, and dissolve. A transition effect is signalled in a transition effect property structure, which is associated with the first of the two consecutive items involved in the transition, indicates the transition type, and possibly signals other transition information, such as transition direction and transition shape, when applicable.

4. Examples of Technical Problems Solved by Disclosed Technical Solutions

The latest designs of VVC image file format and signalling of image transition effects have the following problems:

-   -   1) In slideshows or other types of image based applications that         involve a transition effect from one image to another, although         the time period for a transition often does not need to be         precise, for a good user experience, it should not be too long,         and it should not be too short, either. And the best transition         period is content and transition type dependent. Therefore, it         would be helpful from use experience point of view to signal a         recommended transition period, where the recommended value is         determined by the content creator.     -   2) In the latest VVC image file format draft specification, the         specified VVC image item types and file brands allow the VVC         bitstream of an image item to include an access unit containing         multiple pictures of multiple layers, where some of pictures may         be inter coded, i.e., containing predicted B or P slices using         inter-layer prediction as specified in VVC. In other words,         there lacks an interoperability point, either through an image         item type or a file brand, wherein an image item can only         contain one picture that is intra coded (i.e., containing only         intra-coded I slices). In the VVC standard itself, such         interoperability point has been provided through the definitions         of the two still picture profiles, the Main 10 Still Picture         profile and the Main 10 4:4:4 Still Picture profile.     -   3) An item of type ‘vvc1’ is specified as follows:         -   An item of type ‘vvc1’ consists of the NAL units of a VVC             bitstream that are length-delimited as specified below, and             the bitstream contains exactly one access unit.         -   NOTE 2 An item of type ‘vvc1’ may consists of an IRAP access             unit as defined in ISO/JEC 23090-3, can contain more than             one coded picture, and contains at most one coded picture             with any specific value of nuh_layer_id.         -   However, not any access unit can be the access unit in such             an image item. Therefore, the first part of the above NOTE 2             should be moved to the basic definition (i.e., the first             sentence quoted above), and the missing piece of GDR access             unit should be added.     -   4) The following sentence exists:         -   The ‘vvc1’ image item shall include the layers that are             included in the layer set identified by the associated             TargetOlsProperty and may include other layers too.         -   If to allow for other layers than layers contained in the             identified OLS, then which entity in the application system             is supposed to set the right value of target OLS index in             the associated TargetOlsProperty? Since in any case this             value needs to be set correctly, e.g., by the file composer,             throwing away the unnecessary pictures in the unnecessary             layers would also be an easy operation by the file composer,             so it would make sense to not allow unnecessary pictures in             the unnecessary layers at all.     -   5) The following constraint exists:         -   Image items originating from the same bitstream shall be             associated with the same             VvcOperatingPointsInformationProperty.     -   However, a VVC bitstream may include multiple CVSs that may have         different operating points.     -   6) In the following text, the values of some other syntax         elements of VvcOperatingPointsRecord, such as         ptl_max_temporal_id[i] (the temporal ID of the highest sub-layer         representation for which the level information is present in the         i-th profile_tier_level( ) syntax structure) and         op_max_temporal_id, should also be constrained:         -   When included in VvcOperatingPointsInformationProperty, the             values of the syntax elements of VvcOperatingPointsRecord             are constrained as follows:             -   frame_rate_info_flag shall be equal to 0. Consequently,                 avgFrameRate and constantFrameRate are not present and                 their semantics are not specified.             -   bit_rate_info_flag shall be equal to 0. Consequently,                 maxBitRate and avgBitRate are not present and their                 semantics are not specified.     -   7) The following text exists:         -   If the VVC subpicture item is suitable to be decoded with a             VVC decoder and to be consumed without other VVC subpicture             items, the VVC subpicture item shall be stored as an item of             type ‘vvc1’. Otherwise the VVC subpicture item shall be             stored as an item of type ‘vvs1’ and formatted as a series             of NAL units preceded by length fields, as defined in             L.2.2.1.2.         -   Which has the following issues:             -   a) This condition is not clear enough to be used as a                 condition for a conformance requirement (e.g., when                 thinking about how to check whether the requirement is                 fulfilled), and thus needs to be clarified.             -   b) The use of image item of type ‘vvc1’ is not exactly                 aligned with the earlier definition that the bitstream                 contains exactly one VVC access unit, as herein the                 bitstream of an image item of type ‘vvc1’ can contain                 just a subset of a VVC access unit.             -   c) It is not clear whether it is allowed to have one VVC                 image item, say of type ‘vvc1’, that contains a picture                 containing multiple “extractable” subpictures.     -   8) The following statement does not include OPI NAL units:         -   VPS, DCI, SPS, PPS, AUD, PH, EOS, and EOB NAL units shall be             absent both in item and in the samples of ‘vvs1’ items.     -   However, the operating point information (OPI) NAL units should         be handled similarly herein.     -   9) Only one transition effect (e.g., zoom, rotation) is allowed         for a given image or a region within a given image. However, in         real applications, multiple effects may be applied to one image         or one region within a given image.     -   10) The specification of the VVC image sequence brand involves         the VVC profiles through the following phrase: “for which         general_profile_idc is equal to 1 or         (general_profile_compatibility_flags & 2(32−1)) is greater than         0”. However, general_profile_idc equal to 1 in VVC is the Main         10 profile, that means other VVC profiles are not allowed.

5. Example Embodiments and Solutions

To solve the above problems, and others, methods as summarized below are disclosed.

The items should be considered as examples to explain the general concepts and should not be interpreted in a narrow way. Furthermore, these items can be applied individually or combined in any manner.

-   -   1) To solve problem 1, a recommended transition period may be         signalled for a transition from one image to another.         -   a. In one example, alternatively, a mandatory transition             period is signalled for a transition from one image to             another.         -   b. In one example, the value of the signalled value, a             recommended or mandatory transition period, is determined by             the content creator.         -   c. In one example, one transition period is signalled for             each transition property.         -   d. In one example, one transition period is signalled for             each type of transitions.         -   e. In one example, one transition period is signalled for a             list of transition properties.         -   f. In one example, one transition period is signalled for a             list of types of transitions.         -   g. In one example, one transition period is signalled for             all transitions.         -   h. In one example, the transition period is signalled as an             M-bit (e.g., 8-bit) unsigned integer value in units of             seconds, M being a positive integer.             -   i. Alternatively, the transition period is signalled as                 N-bit (e.g., 16-bit) unsigned integer value in units of                 1/X, where X is a positive integer (e.g., ⅛, 1/16, 1/32,                 1/64, 1/128, 1/256, etc.) seconds.             -   ii. Alternatively, the transition period is signalled as                 N-bit (e.g., 16-bit) unsigned integer value in units of                 pictures or frames.             -   iii. Alternatively, the signalling method for the                 transition period may be the same for all kinds of                 transition properties that are applicable, (e.g., using                 the same unit and/or length in bits).             -   iv. Alternatively, the signalling method for the                 transition period may be different for different kinds                 of transition properties that are applicable (e.g.,                 using different units or lengths in bits).             -   v. Alternatively, instead of using the fixed length in                 bits (e.g., M bits or N bits), the length in bits may be                 further signalled.                 -   i. Alternatively, furthermore, the transition period                     may be signalled as u(v) wherein v represents the                     length in bits.             -   vi. Alternatively, instead of using the fixed length in                 bits (e.g., M bits or N bits), the transition period may                 be signalled with other methods, such as ue(v).     -   2) To solve problem 2, one or more than one file brand is         defined, such that the VVC bitstream contained in an image item         conforming to such a brand is required to contain only one         access unit that contains only one picture (or a part thereof)         that is intra coded.         -   a. Alternatively, one or more than one file brand is             defined, such that the VVC bitstream contained in an image             item conforming to such a brand is required to contain only             one access unit that contains only one picture (or a part             thereof) that is intra/IBC/Palette coded.             -   i. Alternatively, one or more than one file brand is                 defined, such that the VVC bitstream contained in an                 image item conforming to such a brand is required to                 contain only one access unit that contains only one I                 picture (or a part thereof).         -   b. In one example, the value of such a file brand is             specified as ‘vvic’, ‘vvi1’, ‘vvi2’.         -   c. In one example, additionally, the VVC bitstream contained             in such an image item is required to conform to the Main 10             Still Picture profile, the Main 10 4:4:4 Still Picture             profile, the Main 10 profile, the Main 10 4:4:4 profile, the             Multilayer Main 10 profile, or the Multilayer Main 10 4:4:4             profile.             -   i. Alternatively, additionally, the VVC bitstream                 contained in such an image item is required to conform                 to the Main 10 Still Picture profile, the Main 10 4:4:4                 Still Picture profile, the Main 10 profile, or the Main                 10 4:4:4 profile.             -   ii. Alternatively, additionally, the VVC bitstream                 contained in such an image item is required to conform                 to the Main 10 Still Picture profile or the Main 10                 4:4:4 Still Picture profile.         -   d. In one example, it may be specified that an image item             conforming to such a brand shall not have any of the             following properties: target output layer set property             (TargetOlsProperty), VVC operating points information             property (VvcOperatingPointsInformationProperty).     -   3) To solve problem 2, one or more than one image item type is         defined, such that the VVC bitstream contained in an image item         of such a type contains only one access unit that contains only         picture that is intra coded.         -   a. Alternatively, one or more than one image item type is             defined, such that the VVC bitstream contained in an image             item of such a type contains only one access unit that             contains only picture that is intra/palette/IBC coded.             -   i. Alternatively, one or more than one image item type                 is defined, such that the VVC bitstream contained in an                 image item of such a type contains only one access unit                 that contains only I pictures.         -   b. In one example, the type value of such an image item type             is specified as ‘vvc1’ or ‘vvc2’.         -   c. In one example, additionally, the bitstream in such an             image item is required to conform to the Main 10 Still             Picture profile, the Main 10 4:4:4 Still Picture profile,             the Main 10 profile, the Main 10 4:4:4 profile, the             Multilayer Main 10 profile, or the Multilayer Main 10 4:4:4             profile.             -   i. Alternatively, additionally, the bitstream in such an                 image item is required to conform to the Main 10 Still                 Picture profile, the Main 10 4:4:4 Still Picture                 profile, the Main 10 profile, or the Main 10 4:4:4                 profile.             -   ii. Alternatively, additionally, the bitstream in such                 an image item is required to conform to the Main 10                 Still Picture profile or the Main 10 4:4:4 Still Picture                 profile.         -   d. In one example, it may be specified that an image item of             such a type shall not have any of the following properties:             target output layer set property (TargetOlsProperty), VVC             operating points information property             (VvcOperatingPointsInformationProperty).     -   4) To solve problem 3, a VVC image item, e.g., of type ‘vvc1’,         is defined to consist of the NAL units of a VVC bitstream that         contains exactly one access unit that is an IRAP access unit as         defined in ISO/IEC 23090-3 or an GDR access unit for which all         pictures have ph_recovery_poc_cnt equal to 0 as defined in         ISO/IEC 23090-3.     -   5) To solve problem 4, it is disallowed for a VVC image item,         e.g., of type ‘vvc1’, to contain pictures in layers that do not         belong to the target output layer set.     -   6) To solve problem 5, it is allowed for image items originating         from the same bitstream to be associated with different         instances of VvcOperatingPointsInformationProperty.     -   7) To solve problem 6, the syntax element ptl_max_temporal_id[i]         and op_max_temporal_id of VvcOperatingPointsRecord are         constrained to be certain values when VvcOperatingPointsRecord         is included in VvcOperatingPointsInformationProperty.     -   8) To solve problem 7, it may be specified that either of the         following is allowed for a VVC image item, e.g., of type ‘vvc1’:         -   a. Contains an entire VVC access unit, wherein each picture             may contain multiple “extractable” subpictures.         -   b. Contains a subset of a VVC access unit, wherein for each             layer present in the bitstream, there is one or more             “extractable” subpictures that collectively form a             rectangular region.     -   Where an “extractable” subpicture refers to a subpicture for         which the corresponding flag sps_subpic_treated_as_pic_flag[i]         as specified in VVC is equal to 1.     -   9) To solve problem 8, it may be specified that OPI NAL units         shall be absent both in item and in the samples of ‘vvs1’ items.     -   10) To solve problem 9, it is proposed to allow multiple         transition effects from one image (or a region thereof) to         another image (or a region thereof) in a slideshow.         -   a. In one example, indications of multiple transition             effects may be signaled, e.g., by having multiple transition             effect property structures associated with the first of two             consecutive image items.         -   b. In one example, an indication of the number of transition             effects to be applied to two consecutive image items may be             signaled in the file.         -   c. Alternatively, furthermore, how to apply the multiple             transition effects may be signaled in the file or predefined             or derived-on-the-fly.             -   i. In one example, the order for applying the multiple                 transition effects may be signaled in the file.             -   ii. In one example, the order for applying the multiple                 transition effects may be derived according to the order                 of indications of the multiple effects in the bitstream.     -   11) To solve problem 9, it is proposed to allow multiple         transition effects from one image to another image in a         slideshow, wherein each of the multiple transition effects         applies to a particular region in the two image items involved         in the transition.         -   a. In one example, the particular region in the two image             items involved in the transition to which the transition             effect applies is signaled in the transition effect             property.     -   12) To solve problem 9, it is proposed to allow multiple         alternative transition effects to be signalled for a pair of         consecutive image items, and it is up to the player of the file         to choose one of the multiple transition effects to be applied.         -   a. In one example, the priority order (or preference order)             of the multiple transition effects is signaled in the file             or predefined or derived according to the order of the             signalling of the transition properties.     -   13) To solve problem 10, it is proposed that the VVC image         sequence brand is specified to be agnostic to VVC profiles, such         that any VVC profile may be applied.

6. Embodiments

Below are some example embodiments for some of the invention aspects summarized above in Section 5, which can be applied to the standard specification for VVC image file format and support of slideshows. Most relevant parts that have been added or modified are underlined in boldface italics, and some of the deleted parts are indicated using [[ ]].

6.1. First Embodiment

This embodiment is for at least items 1, 1.b, and 1.c.

6.5.28 Wipe Transition Effect 6.5.28.1 Definition

-   -   Box type: ‘wipe’     -   Property type: Transformative item property     -   Container: ItemPropertyContainerBox     -   Mandatory (per item): No     -   Quantity (per item): At most one         The WipeTransitionEffectProperty documents the suggested wipe         transition effect (an image item gradually replaces another from         one side of the image item to another) to apply between the         display of two consecutive items of a Slideshow entity group.         This item property shall be associated with the first of the two         consecutive items involved in the transition.         This item property shall be associated with an image item after         the association of any other descriptive or transformative         properties.

6.5.28.2 Syntax

-   -   aligned(8) class WipeTransitionEffectProperty     -   extends ItemFullProperty(‘wipe’, version=0, flags=0) {         -   unsigned int(8) transition_direction;         -   unsigned int(8) transition period;     -   }

6.5.28.3 Semantics

-   -   transition_direction identifies the transition direction to         apply. It takes one of the following values:         -   0: from-left;         -   1: from-right;         -   2: from-top;         -   3: from-bottom;         -   4: from-left-top;         -   5: from-right-top;         -   6: from-left-bottom;         -   7: from-right-bottom;         -   Other values are-reserved.     -   transition_period indicates the recommended transition period,         in units of seconds, i.e., the time period from the start to the         end of the transition. The value equal to 0 indicates that no         transition period is recommended.

6.5.29 Zoom Transition Effect 6.5.29.1 Definition

-   -   Box type: ‘ zoom’     -   Property type: Transformative item property     -   Container: ItemPropertyContainerBox     -   Mandatory (per item): No     -   Quantity (per item): At most one         The ZoomTransitionEffectProperty documents the suggested zoom         transition effect (an image item replaces another by zoom-in or         zoom-out from another image item) to apply between the display         of two consecutive items of a Slideshow entity group.         This item property shall be associated with the first of the two         consecutive items involved in the transition.         This item property shall be associated with an image item after         the association of any other descriptive or transformative         properties.

6.5.29.2 Syntax

-   -   aligned(8) class ZoomTransitionEffectProperty     -   extends ItemFullProperty(‘zoom’, version=0, flags=0) {         -   unsigned int(1) transition_direction;         -   unsigned int(7) transition_shape;         -   unsigned int(8) transition period;     -   }

6.5.29.3 Semantics

-   -   transition_direction identifies the transition direction to         apply. It takes one of the following values:         -   0: in; (zoom-in using the shape defined by transition_shape)         -   1: out; (zoom-out using the shape defined by             transition_shape) transition_shape identifies the transition             shape to apply. It takes one of the following values         -   0: rectangular;         -   1: circle;         -   2: diamond;         -   Other values are reserved.     -   transition_period indicates the recommended transition period,         in units of seconds, i.e., the time period from the start to the         end of the transition. The value equal to 0 indicates that no         transition period is recommended.

6.5.30 Fade Transition Effect 6.5.30.1 Definition

-   -   Box type: ‘fade’     -   Property type: Transformative item property     -   Container: ItemPropertyContainerBox     -   Mandatory (per item): No     -   Quantity (per item): At most one         The FadeTransitionEffectProperty documents the suggested fade         transition effect (an image item replaces another by first         gradually transitioning to a white or black image and then         gradually transitioning from this white or black image to the         new image item) to apply between the display of two consecutive         items of a Slideshow entity group.         This item property shall be associated with the first of the two         consecutive items.         This item property shall be associated with an image item after         the association of any other descriptive or transformative         properties.

6.5.30.2 Syntax

-   -   aligned(8) class FadeTransitionEffectProperty     -   extends ItemFullProperty(‘fade’, version=0, flags=0) {         -   unsigned int(8) transition_direction;         -   unsigned int(8) transition period;     -   }

6.5.30.3 Semantics

-   -   transition_direction identifies the transitioning image to use.         It takes one of the following values:         -   0: through_white;         -   1: through_black;         -   Other values are reserved.     -   transition_period indicates the recommended transition period,         in units of seconds, i.e., the time period from the start to the         end of the transition. The value equal to 0 indicates that no         transition period is recommended.

6.5.31 Split Transition Effect 6.5.31.1 Definition

-   -   Box type: ‘split’     -   Property type: Transformative item property     -   Container: ItemPropertyContainerBox     -   Mandatory (per item): No     -   Quantity (per item): At most one         The SplitTransitionEffectProperty documents the suggested split         transition effect (an image item gradually replaces another         image item by first being horizontally or vertically split) to         apply between the display of two consecutive items of a         Slideshow entity group.         This item property shall be associated with the first of the two         consecutive items.         This item property shall be associated with an image item after         the association of any other descriptive or transformative         properties.

6.5.31.2 Syntax

-   -   aligned(8) class SplitTransitionEffectProperty     -   extends ItemFullProperty(‘split’, version=0, flags=0) {         -   unsigned int(8) transition_direction;         -   unsigned int(8) transition period;     -   }

6.5.31.3 Semantics

-   -   transition_direction identifies the transitioning direction to         apply. It takes one of the following values:         -   0: vertical_in;         -   1: vertical_out;         -   2: horizontal_in;         -   3: horizontal_out;         -   Other values are reserved.     -   transition_period indicates the recommended transition period,         in units of seconds, i.e., the time period from the start to the         end of the transition. The value equal to 0 indicates that no         transition period is recommended.

6.5.32 Dissolve Transition Effect 6.5.32.1 Definition

-   -   Box type: ‘dsvl’     -   Property type: Transformative item property     -   Container: ItemPropertyContainerBox     -   Mandatory (per item): No     -   Quantity (per item): At most one         The DissolveTransitionEffect Property documents the suggested         dissolve transition effect (an image item replaces another by         gradually fading in while the other image item is gradually         fading out) to apply between the display of two consecutive         items of a Slideshow entity group.         This item property shall be associated with the first of the two         consecutive items.         This item property shall be associated with an image item after         the association of any other descriptive or transformative         properties.

6.5.32.2 Syntax

-   -   aligned(8) class DissolveTransitionEffectProperty     -   extends ItemFullProperty(‘dsvl’, version=0, flags=0) {         -   unsigned int (8) transition_period;     -   }

6.5.32.3 Semantics

-   -   transition_period indicates the recommended transition period,         in units of seconds, i.e., the time period from the start to the         end of the transition. The value equal to 0 indicates that no         transition period is recommended.         6.8         Add the following new subclause after subclause 6.8.8:

6.5.33 Slideshow 6.8.9.1 ‘Slid’ Entity Group

The Slideshow entity group (‘slid’) indicates a set of entities that are intended to form a slideshow. This entity group shall contain entity_id values that point to image items and shall contain no entity_id values that point to tracks.

-   -   NOTE 1 An input image item may be a derived item (e.g. identity,         overlay or grid) for advanced slideshows requiring composition         of images (possibly onto a canvas).         The entity_id values of the input slideshow images in a         Slideshow entity group shall be listed in increasing display         order.         There may be multiple Slideshow entity groups in the same file         with different group_id values.         A transition effect item property may be associated with an         image item of the Slideshow entity group to document the         transition effect to apply between this image item and the         consecutive image item in the list of entities.     -   NOTE 2 When a same image needs to be included in different         slideshows, it is possible to associate it with a different         transition effect in a different slideshow either by using a         derived item of type ‘iden’ in a different slideshow associated         with a different transition effect or by having two items that         share same data (via ‘iloc’) but having a different transition         effect in different slideshows.     -   NOTE 3 Transition effect item properties should only be marked         as essential if they truly are so, as an unrecognized transition         property that is marked as essential might impede displaying of         a single image. In most slideshows the transition effects are         ‘nice to have’ but they should not prevent displaying an image         if the reader doesn't understand the transition effect.

6.2. Second Embodiment

This embodiment is at least for items 4 and 5.

L.2.2.1.2 Image Item of Type ‘vvc1’

An item of type ‘ vvc1’ consists of the NAL units of a VVC bitstream that are length-delimited as specified below, and the bitstream contains exactly access unit that is an IRAP access unit as defined in ISO/IEC 23090-3 or an GDR access unit for which all pictures have ph recovery poc cnt equal to 0 as defined in ISO/IEC 23090-3. NAL units with nuh_layer_id greater than 0 may be present in items of type ‘vvc1’. Readers shall process NAL units with nuh_layer_id greater than 0 in an item of type ‘vvc1’ in a similar manner as NAL units with nuh_layer_id equal to 0.

-   -   NOTE 1 In an image item of type ‘vvc1’, pictures in         non-independent layers may use inter-layer prediction and hence         may contain inter coded slices. A picture that does not use         inter-layer prediction in an image item may be an IDR or CRA         picture or a GDR picture with ph_recovery_poc_cnt equal to 0 as         defined ISO/IEC 23090-3.     -   NOTE 2 An item of type ‘vvc1’ [[may consists of an IRAP access         unit as defined in ISO/IEC 23090-3, can contain more than one         coded picture, and]] contains at most one coded picture with any         specific value of nuh_layer_id.         All image items of type ‘vvc1’ with multiple layers shall have         an associated item property         VvcOperatingPointsInformationProperty. The         VvcOperatingPointsInformationProperty provides a summary of the         high-level characteristics of the bitstream contained in the         image item with multiple layers, similar to the ‘vopi’ sample         grouping of ISO/IEC 14496-15.         All image items of type ‘vvc1’ shall have zero or one associated         item property TargetOlsProperty. The TargetOlsProperty contains         the target_ols_idx, which provides the output layer set index to         be used as input for the decoding process of VVC coded image         item. The target_ols_idx is used as the value of the         TargetOlsIdx variable and is specified in the same coding format         as in VVC. The number of TargetOls Property shall not be zero         unless there is only one picture in the image item. The ‘vvc1’         image item shall include the layers that are included in the         output layer set identified by the associated TargetOlsProperty         and [[may include other layers too]] shall not include other         layers.         An image item of type ‘vvc1’ may have an associated item         property LayerSelectorProperty. The LayerSelectorProperty shall         contain layer_id that is among the nuh_layer_id values of the         output layers of the output layer set identified by         TargetOlsProperty associated with the same image item.

6.3. Third Embodiment

This embodiment is at least for items 6 and 7.

L.2.3.3 VVC Operating Points Information Property L.2.3.3.1 Definition

-   -   Box type: ‘vopi’     -   Property type: Descriptive item property     -   Container: ItemPropertyContainerBox     -   Mandatory (per item): No, for an image item of type ‘vvc1’     -   Quantity (per item): Zero or one for an image item of type         ‘vvc1’         The VvcOperatingPointsInformationProperty is similar to the         VvcOperatingPointsInformation specified in ISO/IEC 14496-15 but         applies to image items. [[Image items originating from the same         bitstream shall be associated with the same         VvcOperatingPointsInformationProperty.]] The         VvcOperatingPointsInformationProperty informs about the         different operating points provided by a bitstream and their         constitution. Each operating point is related to an output layer         set and a combination of a profile, tier and level. TargetOls         Property associated with an image item provides the output layer         set index that can be used to select which         operating-point-specific information of the         VvcOperatingPointsInformationProperty applies to the image item.         The VvcOperatingPointsInformationProperty also provides the         dependency information between layers.

L.2.3.3.2 Syntax

-   -   aligned(8) class VvcOperatingPointsInformationProperty     -   extends ItemFullProperty(‘vopi’, version=0, flags=0) {         -   VvcOperatingPointsRecord; // specified in ISO/IEC 14496-15     -   }

L.2.3.3.3 Semantics

The semantics of VvcOperatingPointsRecord are specified in ISO/IEC 14496-15. When included in VvcOperatingPointsInformationProperty, the values of the syntax elements of VvcOperatingPointsRecord are constrained as follows:

-   -   ptl_max_temporal_id[i] for each value of i in the range of 0 to         num_profile_tier_level_minus1, inclusive, shall be equal to 0.     -   max_temporal_id shall be equal to 0.     -   frame_rate_info_flag shall be equal to 0. Consequently,         avgFrameRate and constantFrameRate are not present and their         semantics are not specified.     -   bit_rate_info_flag shall be equal to 0. Consequently, maxBitRate         and avgBitRate are not present and their semantics are not         specified.

6.4. Fourth Embodiment

This embodiment is at least for item 9.

VVC Subpicture Items

ISO/IEC 23090-3 allows partitioning of a picture into subpictures. ISO/IEC 23090-3 includes the exact definition and the signalling of the properties of a subpicture, while some properties are informatively repeated in the following:

-   -   A subpicture is a rectangular region of a picture with one or         more slices.     -   A subpicture may be decoded independently of other subpictures,         if [[there are no intra prediction, entropy decoding and loop         filter dependencies between subpictures]] the subpicture         boundaries are treated as picture boundaries in the inter         prediction process (i.e., when the corresponding flag_sps_subpic         treated as pic flag[i] as specified in ISO/IEC 23090-3 is equal         to 1).         If the VVC subpicture item is suitable to be decoded with a VVC         decoder and to be consumed without other VVC subpicture items,         the VVC subpicture item shall be stored as an item of type         ‘vvc1’. Otherwise the VVC subpicture item shall be stored as an         item of type ‘vvs1’ and formatted as a series of NAL units         preceded by length fields, as defined in L.2.2.1.2.         A subpicture item stored as type ‘vvc1’ shall follow all the         requirements of subclause L.2.2.1.2.         When the VVC subpicture item is stored as an item of type         ‘vvs1’, the following constraints apply for the item:     -   A set of VCL NAL units containing one or more subpictures, as         defined in ISO/IEC 23090-3, such that the subpictures contained         in the set of VCL NAL units represent a rectangular array of         pixels;     -   VPS, DCI, OPI, SPS, PPS, AUD, PH, EOS, and EOB NAL units shall         be absent both in item and in the samples of ‘vvs1’ items.     -   The item shall be associated with a ‘vvnc’ item property with         the syntax and semantics identical to VvcNALUConfigBox as         specified in ISO/IEC 14496-15.     -   NOTE NAL units with nuh_layer_id greater than 0 may be present         in items of type ‘vvs1’.     -   Readers shall process NAL units with nuh_layer_id greater than 0         in an item of type ‘vvs1’ in a similar manner as NAL units with         nuh_layer_id equal to 0.         The decoding order of a VVC subpicture item is determined by a         VVC base item which is defined in subclause L.2.5.

6.5. Fifth Embodiment

This embodiment is at least for item 13.

L.4.2 VVC Image Sequence Brands L.4.2.1 General

The brand ‘ vvcc’ is specified in the following subclauses.

L.4.2.2 Requirements on Files

Files shall include ‘msf1’ among the compatible brands and hence conform to the specifications in 10.3.1.1. Additionally, files shall comply with the specifications in L.3. track_enabled shall be equal to 1 and track_in_movie shall be equal to 1 for at least one image sequence track conforming to with the specifications in L.3. When the ‘vvcc’ brand is among the compatible brands, there shall be an image sequence track with ‘vvc1’ sample entry type, track_enabled equal to 1, track_in_movie equal to 1, and each sample entry having a data_reference_index value such that it is mapped to a DataEntryBox with (entry_flags & 1) equal to 1[[, for which general_profile_idc is equal to 1 or (general_profile_compatibility_flags & 2⁽³²⁻¹⁾) is greater than 0]].

-   -   NOTE In other words, when the ‘vvcc’ brand is among the         compatible brands, at least one viewable image sequence track is         an VVC image sequence track and contains a bitstream conforming         to the VVC.

L.4.2.3 Requirements on Readers

The requirements on readers specified in 10.3.1.2 shall be supported.

Readers for the ‘vvcc’ brand shall be able to display an image sequence track with ‘vvc1’ sample entry type, track_enabled equal to 1 and track_in_movie equal to 1[[, for which general_profile_idc is equal to 1 or [general_profile_compatibility_flags & 2⁽³²⁻¹⁾] is greater than 0]]. Readers shall support all values allowed by 7.2.1 for the matrix syntax element of the TrackHeaderBox and shall obey the CleanApertureBox of the visual sample entry when displaying an image sequence track with ‘vvc1’ sample entry.

-   -   NOTE In other words, readers are required to support rotation by         0, 90, 180, and 270 degrees and mirroring, as controlled by the         matrix syntax element, as well as cropping, as controlled by the         CleanApertureBox.

FIG. 1 is a block diagram showing an example video processing system 1900 in which various techniques disclosed herein may be implemented. Various implementations may include some or all of the components of the system 1900. The system 1900 may include input 1902 for receiving video content. The video content may be received in a raw or uncompressed format, e.g., 8 or 10 bit multi-component pixel values, or may be in a compressed or encoded format. The input 1902 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interface include wired interfaces such as Ethernet, passive optical network (PON), etc. and wireless interfaces such as Wi-Fi or cellular interfaces.

The system 1900 may include a coding component 1904 that may implement the various coding or encoding methods described in the present document. The coding component 1904 may reduce the average bitrate of video from the input 1902 to the output of the coding component 1904 to produce a coded representation of the video. The coding techniques are therefore sometimes called video compression or video transcoding techniques. The output of the coding component 1904 may be either stored, or transmitted via a communication connected, as represented by the component 1906. The stored or communicated bitstream (or coded) representation of the video received at the input 1902 may be used by the component 1908 for generating pixel values or displayable video that is sent to a display interface 1910. The process of generating user-viewable video from the bitstream representation is sometimes called video decompression. Furthermore, while certain video processing operations are referred to as “coding” operations or tools, it will be appreciated that the coding tools or operations are used at an encoder and corresponding decoding tools or operations that reverse the results of the coding will be performed by a decoder.

Examples of a peripheral bus interface or a display interface may include universal serial bus (USB) or high definition multimedia interface (HDMI) or Displayport, and so on. Examples of storage interfaces include SATA (serial advanced technology attachment), PCI, IDE interface, and the like. The techniques described in the present document may be embodied in various electronic devices such as mobile phones, laptops, smartphones or other devices that are capable of performing digital data processing and/or video display.

FIG. 2 is a block diagram of a video processing apparatus 3600. The apparatus 3600 may be used to implement one or more of the methods described herein. The apparatus 3600 may be embodied in a smartphone, tablet, computer, Internet of Things (IoT) receiver, and so on. The apparatus 3600 may include one or more processors 3602, one or more memories 3604 and video processing hardware 3606. The processor(s) 3602 may be configured to implement one or more methods described in the present document. The memory (memories) 3604 may be used for storing data and code used for implementing the methods and techniques described herein. The video processing hardware 3606 may be used to implement, in hardware circuitry, some techniques described in the present document. In some embodiments, the video processing hardware 3606 may be at least partly included in the processor 3602, e.g., a graphics co-processor.

FIG. 4 is a block diagram that illustrates an example video coding system 100 that may utilize the techniques of this disclosure.

As shown in FIG. 4 , video coding system 100 may include a source device 110 and a destination device 120. Source device 110 generates encoded video data which may be referred to as a video encoding device. Destination device 120 may decode the encoded video data generated by source device 110 which may be referred to as a video decoding device.

Source device 110 may include a video source 112, a video encoder 114, and an input/output (I/O) interface 116.

Video source 112 may include a source such as a video capture device, an interface to receive video data from a video content provider, and/or a computer graphics system for generating video data, or a combination of such sources. The video data may comprise one or more pictures. Video encoder 114 encodes the video data from video source 112 to generate a bitstream. The bitstream may include a sequence of bits that form a coded representation of the video data. The bitstream may include coded pictures and associated data. The coded picture is a coded representation of a picture. The associated data may include sequence parameter sets, picture parameter sets, and other syntax structures. I/O interface 116 may include a modulator/demodulator (modem) and/or a transmitter. The encoded video data may be transmitted directly to destination device 120 via I/O interface 116 through network 130 a. The encoded video data may also be stored onto a storage medium/server 130 b for access by destination device 120.

Destination device 120 may include an I/O interface 126, a video decoder 124, and a display device 122.

I/O interface 126 may include a receiver and/or a modem. I/O interface 126 may acquire encoded video data from the source device 110 or the storage medium/server 130 b. Video decoder 124 may decode the encoded video data. Display device 122 may display the decoded video data to a user. Display device 122 may be integrated with the destination device 120, or may be external to destination device 120 which be configured to interface with an external display device.

Video encoder 114 and video decoder 124 may operate according to a video compression standard, such as the High Efficiency Video Coding (HEVC) standard, Versatile Video Coding (VVM) standard and other current and/or further standards.

FIG. 5 is a block diagram illustrating an example of video encoder 200, which may be video encoder 114 in the system 100 illustrated in FIG. 4 .

Video encoder 200 may be configured to perform any or all of the techniques of this disclosure. In the example of FIG. 5 , video encoder 200 includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of video encoder 200. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

The functional components of video encoder 200 may include a partition unit 201, a predication unit 202 which may include a mode select unit 203, a motion estimation unit 204, a motion compensation unit 205 and an intra prediction unit 206, a residual generation unit 207, a transform unit 208, a quantization unit 209, an inverse quantization unit 210, an inverse transform unit 211, a reconstruction unit 212, a buffer 213, and an entropy encoding unit 214.

In other examples, video encoder 200 may include more, fewer, or different functional components. In an example, predication unit 202 may include an intra block copy (IBC) unit. The IBC unit may perform predication in an IBC mode in which at least one reference picture is a picture where the current video block is located.

Furthermore, some components, such as motion estimation unit 204 and motion compensation unit 205 may be highly integrated, but are represented in the example of FIG. 5 separately for purposes of explanation.

Partition unit 201 may partition a picture into one or more video blocks. Video encoder 200 and video decoder 300 may support various video block sizes.

Mode select unit 203 may select one of the coding modes, intra or inter, e.g., based on error results, and provide the resulting intra- or inter-coded block to a residual generation unit 207 to generate residual block data and to a reconstruction unit 212 to reconstruct the encoded block for use as a reference picture. In some example, Mode select unit 203 may select a combination of intra and inter predication (CIIP) mode in which the predication is based on an inter predication signal and an intra predication signal. Mode select unit 203 may also select a resolution for a motion vector (e.g., a sub-pixel or integer pixel precision) for the block in the case of inter-predication.

To perform inter prediction on a current video block, motion estimation unit 204 may generate motion information for the current video block by comparing one or more reference frames from buffer 213 to the current video block. Motion compensation unit 205 may determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from buffer 213 other than the picture associated with the current video block.

Motion estimation unit 204 and motion compensation unit 205 may perform different operations for a current video block, for example, depending on whether the current video block is in an I slice, a P slice, or a B slice.

In some examples, motion estimation unit 204 may perform uni-directional prediction for the current video block, and motion estimation unit 204 may search reference pictures of list 0 or list 1 for a reference video block for the current video block. Motion estimation unit 204 may then generate a reference index that indicates the reference picture in list 0 or list 1 that contains the reference video block and a motion vector that indicates a spatial displacement between the current video block and the reference video block. Motion estimation unit 204 may output the reference index, a prediction direction indicator, and the motion vector as the motion information of the current video block. Motion compensation unit 205 may generate the predicted video block of the current block based on the reference video block indicated by the motion information of the current video block.

In other examples, motion estimation unit 204 may perform bi-directional prediction for the current video block, motion estimation unit 204 may search the reference pictures in list 0 for a reference video block for the current video block and may also search the reference pictures in list 1 for another reference video block for the current video block. Motion estimation unit 204 may then generate reference indexes that indicate the reference pictures in list 0 and list 1 containing the reference video blocks and motion vectors that indicate spatial displacements between the reference video blocks and the current video block. Motion estimation unit 204 may output the reference indexes and the motion vectors of the current video block as the motion information of the current video block. Motion compensation unit 205 may generate the predicted video block of the current video block based on the reference video blocks indicated by the motion information of the current video block.

In some examples, motion estimation unit 204 may output a full set of motion information for decoding processing of a decoder.

In some examples, motion estimation unit 204 may do not output a full set of motion information for the current video. Rather, motion estimation unit 204 may signal the motion information of the current video block with reference to the motion information of another video block. For example, motion estimation unit 204 may determine that the motion information of the current video block is sufficiently similar to the motion information of a neighboring video block.

In one example, motion estimation unit 204 may indicate, in a syntax structure associated with the current video block, a value that indicates to the video decoder 300 that the current video block has the same motion information as another video block.

In another example, motion estimation unit 204 may identify, in a syntax structure associated with the current video block, another video block and a motion vector difference (MVD). The motion vector difference indicates a difference between the motion vector of the current video block and the motion vector of the indicated video block. The video decoder 300 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

As discussed above, video encoder 200 may predictively signal the motion vector. Two examples of predictive signaling techniques that may be implemented by video encoder 200 include advanced motion vector predication (AMVP) and merge mode signaling.

Intra prediction unit 206 may perform intra prediction on the current video block. When intra prediction unit 206 performs intra prediction on the current video block, intra prediction unit 206 may generate prediction data for the current video block based on decoded samples of other video blocks in the same picture. The prediction data for the current video block may include a predicted video block and various syntax elements.

Residual generation unit 207 may generate residual data for the current video block by subtracting (e.g., indicated by the minus sign) the predicted video block(s) of the current video block from the current video block. The residual data of the current video block may include residual video blocks that correspond to different sample components of the samples in the current video block.

In other examples, there may be no residual data for the current video block for the current video block, for example in a skip mode, and residual generation unit 207 may not perform the subtracting operation.

Transform processing unit 208 may generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to a residual video block associated with the current video block.

After transform processing unit 208 generates a transform coefficient video block associated with the current video block, quantization unit 209 may quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values associated with the current video block.

Inverse quantization unit 210 and inverse transform unit 211 may apply inverse quantization and inverse transforms to the transform coefficient video block, respectively, to reconstruct a residual video block from the transform coefficient video block. Reconstruction unit 212 may add the reconstructed residual video block to corresponding samples from one or more predicted video blocks generated by the predication unit 202 to produce a reconstructed video block associated with the current block for storage in the buffer 213.

After reconstruction unit 212 reconstructs the video block, loop filtering operation may be performed reduce video blocking artifacts in the video block.

Entropy encoding unit 214 may receive data from other functional components of the video encoder 200. When entropy encoding unit 214 receives the data, entropy encoding unit 214 may perform one or more entropy encoding operations to generate entropy encoded data and output a bitstream that includes the entropy encoded data.

FIG. 6 is a block diagram illustrating an example of video decoder 300 which may be video decoder 114 in the system 100 illustrated in FIG. 4 .

The video decoder 300 may be configured to perform any or all of the techniques of this disclosure. In the example of FIG. 6 , the video decoder 300 includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of the video decoder 300. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

In the example of FIG. 6 , video decoder 300 includes an entropy decoding unit 301, a motion compensation unit 302, an intra prediction unit 303, an inverse quantization unit 304, an inverse transformation unit 305, and a reconstruction unit 306 and a buffer 307. Video decoder 300 may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder 200 (FIG. 5 ).

Entropy decoding unit 301 may retrieve an encoded bitstream. The encoded bitstream may include entropy coded video data (e.g., encoded blocks of video data). Entropy decoding unit 301 may decode the entropy coded video data, and from the entropy decoded video data, motion compensation unit 302 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. Motion compensation unit 302 may, for example, determine such information by performing the AMVP and merge mode.

Motion compensation unit 302 may produce motion compensated blocks, possibly performing interpolation based on interpolation filters. Identifiers for interpolation filters to be used with sub-pixel precision may be included in the syntax elements.

Motion compensation unit 302 may use interpolation filters as used by video encoder 200 during encoding of the video block to calculate interpolated values for sub-integer pixels of a reference block. Motion compensation unit 302 may determine the interpolation filters used by video encoder 200 according to received syntax information and use the interpolation filters to produce predictive blocks.

Motion compensation unit 302 may uses some of the syntax information to determine sizes of blocks used to encode frame(s) and/or slice(s) of the encoded video sequence, partition information that describes how each macroblock of a picture of the encoded video sequence is partitioned, modes indicating how each partition is encoded, one or more reference frames (and reference frame lists) for each inter-encoded block, and other information to decode the encoded video sequence.

Intra prediction unit 303 may use intra prediction modes for example received in the bitstream to form a prediction block from spatially adjacent blocks. Inverse quantization unit 303 inverse quantizes, i.e., de-quantizes, the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 301. Inverse transform unit 303 applies an inverse transform.

Reconstruction unit 306 may sum the residual blocks with the corresponding prediction blocks generated by motion compensation unit 202 or intra-prediction unit 303 to form decoded blocks. If desired, a deblocking filter may also be applied to filter the decoded blocks in order to remove blockiness artifacts. The decoded video blocks are then stored in buffer 307, which provides reference blocks for subsequent motion compensation/intra predication and also produces decoded video for presentation on a display device.

A listing of solutions preferred by some embodiments is provided next.

The following solutions show example embodiments of techniques discussed in the previous section (e.g., items 1, 10 and 11).

1. A visual media processing method (e.g., method 700 depicted in FIG. 3 ), comprising: performing (702) a conversion between a visual media comprising a sequence of one or more images and a bitstream representation according to a file format; wherein the file format is configured to include one or more syntax element indicating a transition property between the one or more images during displaying of the one or more images.

2. The method of solution 1, wherein the transition property is a transition time, and wherein the file format includes another syntax element indicative of a type of the transition times, wherein the type comprises a mandatory transition time or a recommended transition time.

3. The method of solution 1, wherein the transition property comprises one or more transition effects between the one or more images.

4. The method of solution 2, wherein the file format includes one or more syntax elements for describing the one or more transition effects applicable to transitions between consecutive images or portions of the consecutive images.

5. The method of solution 3, wherein the file format includes a syntax structure that specifies multiple transition effects and corresponding portions of images to which the multiple transition effects are applicable during transition from one image to a next image.

The following solutions show example embodiments of techniques discussed in the previous section (e.g., item 2).

6. A visual media processing method, comprising: performing a conversion between a visual media comprising a sequence of one or more images and a bitstream representation according to a file format; wherein the file format specifies that, in case that the visual media is represented in a file having a specific file brand, the file format is restricted according a rule.

7. The method of solution 6, wherein the rule specifies to include only one access unit of a portion of an image that is coded using a particular coding tool.

8. The method of solution 6-7, wherein the particular coding tool comprises an intra coding tool.

9. The method of solution 6-7, wherein the particular coding tool comprises an intra block copy coding tool.

10. The method of solution 6, wherein the particular coding tool comprises a palette coding tool.

11. The method of solution 6, wherein the rule specifies that the file format is disallowed from storing the one or more images coded according to a coding property.

12. The method of solution 11, wherein the coding property comprises a target output layer set property.

The following solutions show example embodiments of techniques discussed in the previous section (e.g., items 3, 4, 5 and 8).

13. A visual media processing method, comprising: performing a conversion between a visual media comprising a sequence of one or more images and a bitstream representation according to a file format; wherein the file format is configured to indicate an image type for the one or more images according to a rule.

14. The method of solution 13, wherein the rule specifies that the file format further specifies that, for one image type, the file format allows inclusion of only one access unit that includes an intra coded image.

15. The method of solution 13, wherein the rule specifies that a particular image type is allowed to include only network abstraction layer units that contain exactly one access unit that is an intra random access picture unit.

16. The method of solution 13, wherein the rule specifies that for a particular image type the file format disallows containing pictures in layers that are from different target output layer sets.

17. The method of solution 13, wherein the rule specifies that the file format permits, for a particular image type, to include an entire access unit in which one or more pictures that include multiple extractable subpictures are included.

18. The method of solution 1, wherein the transition proprority corresponds to a transition period, and wherein the one or more syntax elements include a syntax element that indicates the transition period as an unsigned integer value in a first unit of time.

19. The method of solution 18, wherein the syntax element is an M-bit element in units of seconds, wherein M=8.

20. The method of solution 18, wherein the syntax element is an N-bit field in units of 1/X seconds, where N and X are integers.

21. The method of solution 18, wherein the first unit of time corresponds to a frame count of video frames of the video.

22. The method of any of solutions 1-21, wherein the conversion comprises encoding the one or more images to generate the bitstream representation according to the file format.

23. The method of solution 22, wherein the bitstream representation according to the file format is stored on a computer-readable medium or transmitted over a communication connection.

24. The method of any of solutions 1-21, wherein the conversion comprised decoding and reconstructing, from the bitstream representation, the one or more images.

25. The method of solution 24, further including facilitating displaying the one or more images after the decoding and reconstructing.

26. A video decoding apparatus comprising a processor configured to implement a method recited in one or more of solutions 1 to 25.

27. A video encoding apparatus comprising a processor configured to implement a method recited in one or more of solutions 1 to 25.

28. A computer program product having computer code stored thereon, the code, when executed by a processor, causes the processor to implement a method recited in any of solutions 1 to 25.

29. A computer readable medium on which a bitstream representation complying to a file format that is generated according to any of solutions 1 to 25.

30. A method, apparatus or system described in the present document.

In the solutions described herein, an encoder may conform to the format rule by producing a coded representation according to the format rule. In the solutions described herein, a decoder may use the format rule to parse syntax elements in the coded representation with the knowledge of presence and absence of syntax elements according to the format rule to produce decoded video.

FIG. 8 is a flowchart representation of a method for processing image data in accordance with one or more embodiments of the present technology. The method 800 includes, at operation 810, performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of pictures according to a media file format, and the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format. The media file format specifies a suggested transition period of an image item to be applied for a transition between the image item and a next image item during displaying of the pictures as a slideshow.

FIG. 9 is a flowchart representation of a method for processing image data in accordance with one or more embodiments of the present technology. The method 900 includes, at operation 910, performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of pictures according to a media file format, and the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format. The media file format specifies that multiple transition effects are allowable for a transition to be applied between displaying of a first image item and a second image item as a slideshow.

The following are examples of techniques discussed in connection with FIGS. 8-9 .

1. An example method for processing image data, comprising: performing a conversion between a visual media file and a bitstream, wherein the visual media file comprises image items each comprising a sequence of pictures according to a media file format, and wherein the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format, wherein the media file format specifies a transition period of an image item to be applied for a transition between the image item and a next image item during displaying of the pictures as a slideshow.

2. The method of example 1, wherein the media file format specifies that the transition period is a suggested or mandatory field.

3. The method of example 1 or 2, wherein the transition period is specified as an M-bit unsigned integer value.

4. The method of example 2, wherein the transition period is specified as an 8-bit unsigned integer value.

5. The method of example 1 or 2, wherein a number of bits of the transition period varies in a manner dependent on a value of other syntax elements.

6. The method of any of example 1 to 5, wherein the transition period is specified in units of 1/X seconds, wherein X is a positive integer.

7. The method of example 6, wherein the transition period is specified in units of 1/16 seconds.

8. The method of any of example 1 to 5, wherein the transition period is specified in units of pictures or frames.

9. The method of any of example 1 to 8, wherein the transition period is specified for each transition property or each type of transitions.

10. The method of any of example 1 to 9, wherein the transition period is specified for a list of transition properties or a list of types of transitions.

11. An example method for processing image data, comprising: performing a conversion between a visual media file and a bitstream, wherein the visual media file comprises image items each comprising a sequence of pictures according to a media file format, and wherein the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format, wherein the media file format specifies that multiple transition effects are allowable for a transition to be applied between displaying of a first image item and a second image item as a slideshow.

12. The method of example 11, wherein the transition is applicable between a first region of the first image item and a second region of the second image item.

13. The method of example 11 or 12, wherein the media file format further specifies a priority order of applying the multiple transition effects.

14. A video processing apparatus comprising a processor, wherein the processor is configured to perform a method of any of example 1 to 13.

15. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method of any of example 1 to 13 performed by a video processing apparatus.

FIG. 10 is a flowchart representation of a method for processing image data in accordance with one or more embodiments of the present technology. The method 1000 includes, at operation 1010, performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of one or more pictures according to a media file format, and the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format. The video coding format defines multiple profiles. The media file format specifies that the bitstream is represented in a file having a specific brand. The media file format further specifies that one or more profiles used for representing the video in the bitstream are agnostic of the specific brand.

FIG. 11 is a flowchart representation of a method for processing image data in accordance with one or more embodiments of the present technology. The method 1100 includes, at operation 1110, performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of one or more pictures according to a media file format, and the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format. The media file format specifies one or more file brands or one or more image item types associated with the video coding format. The media file format specifies that the bitstream conforms to one of the one or more file brands or one of the one or more image item types includes a single access unit. The single access unit includes a single picture that is at least partially intra-coded.

FIG. 12 is a flowchart representation of a method for processing image data in accordance with one or more embodiments of the present technology. The method 1200 includes, at operation 1210, performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of pictures according to a media file format, and the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format. The file format specifies that an operating point information (OPI) network abstraction layer (NAL) unit is absent in an image item or samples of the image item having a specific image item type.

The following are example solutions of techniques discussed in connection with FIGS. 10-12 .

1. An example solution method for processing image data, comprising: performing a conversion between a visual media file and a bitstream, wherein the visual media file comprises image items each comprising a sequence of one or more pictures according to a media file format, and wherein the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format, wherein the video coding format defines multiple profiles, wherein the media file format specifies that the bitstream is represented in a file having a specific brand, and wherein the media file format further specifies that one or more profiles used for representing the video in the bitstream are agnostic of the specific brand.

2. The method of example solution 1, wherein the video coding format corresponds to a Versatile Video Coding (VVC) standard, wherein the specific brand comprises a VVC brand, and wherein the type corresponding to the specific brand is specified as ‘vvc1’.

3. An example solution method for processing image data, comprising: performing a conversion between a visual media file and a bitstream, wherein the visual media file comprises image items each comprising a sequence of one or more pictures according to a media file format, and wherein the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format, wherein the medium file format specifies one or more file brands or one or more image item types associated with the video coding format, wherein the file format specifies that the bitstream conforms to one of the one or more file brands or one of the one or more image item types includes a single access unit, and wherein the single access unit includes a single picture that is at least partially intra-coded.

4. The method of example solution 3, wherein the video coding standard corresponds to a Versatile Video Coding (VVC) standard.

5. The method of example solution 3 or 4, wherein the single picture is at least partially intra-coded using an intra, an intra-block copy, or a palette coding technique.

6. the method of example solution 5, wherein the single picture is an I picture or a part of an I picture.

7. The method of any of example solution 3 to 6, wherein the one or more file brands are associated with the VVC standard, and wherein a value of a file brand is specified as ‘vvic’, ‘vvi1’, or ‘vvi2’.

8. The method of any of example solution 3 to 6, wherein the one or more image item types are associated with the VVC standard, and wherein a value of an image item type is specified as ‘vvc1’ or ‘vvc2’.

9. The method of any of example solution 3 to 8, wherein the bitstream conforms to a profile that includes at least one of a Main 10 Still Picture profile, a Main 10 4:4:4 Still Picture profile, a Main 10 profile, a Main 10 4:4:4 profile, a Multilayer Main 10 profile, or a Multilayer Main 10 4:4:4 profile.

10. The method of any of example solution 3 to 9, wherein an image item that conforms to the file brand or the image item type excludes a property descriptor, wherein the property descriptor indicates a target output layer set property or a VVC operating points information property.

11. The method of example solution 10, wherein the property descriptor is represented as TargetOlsProperty or VvcOperatingPointsInformationProperty.

12. An example solution method for processing image data, comprising:

performing a conversion between a visual media file and a bitstream, wherein the visual media file comprises image items each comprising a sequence of pictures according to a media file format, and wherein the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format,

wherein the media file format specifies that an operating point information (OPI) network abstraction layer (NAL) unit is absent in an image item or samples of the image item having a specific image item type.

13. The method of example solution 10, wherein the specific image item type is associated with a Versatile Video Coding (VVC) standard, and wherein the specific image item type is specified as ‘vvs1’.

14. A video processing apparatus comprising a processor, wherein the processor is configured to perform a method of any of example solution 1 to 13.

15. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method of any of example solution 1 to 13 performed by a video processing apparatus.

In the present document, the term “video processing” may refer to video encoding, video decoding, video compression or video decompression. For example, video compression algorithms may be applied during conversion from pixel representation of a video to a corresponding bitstream representation or vice versa. The bitstream representation of a current video block may, for example, correspond to bits that are either co-located or spread in different places within the bitstream, as is defined by the syntax. For example, a macroblock may be encoded in terms of transformed and coded error residual values and also using bits in headers and other fields in the bitstream. Furthermore, during conversion, a decoder may parse a bitstream with the knowledge that some fields may be present, or absent, based on the determination, as is described in the above solutions. Similarly, an encoder may determine that certain syntax fields are or are not to be included and generate the coded representation accordingly by including or excluding the syntax fields from the coded representation.

The disclosed and other solutions, examples, embodiments, modules and the functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.

A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

The processes and logic flows described in this document can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random-access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

While this patent document contains many specifics, these should not be construed as limitations on the scope of any subject matter or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular techniques. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

Only a few implementations and examples are described, and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document. 

The invention claimed is:
 1. A method for processing image data, comprising: performing a conversion between a visual media file and a bitstream, wherein the visual media file comprises image items each comprising a sequence of pictures according to a media file format, and wherein the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format, wherein the media file format specifies that an operating point information (OPI) network abstraction layer (NAL) unit is absent in an image item having a specific image item type or samples of the image item, and wherein the media file format further specifies that, in response to a record of operating points being included in a property descriptor of the operating points that indicates high-level characteristics of the bitstream, at least one of a value of a first syntax element in the record or a value of a second syntax element in the record is constrained to be a predetermined value.
 2. The method of claim 1, wherein the conversion includes encoding the visual media file into the bitstream.
 3. The method of claim 1, wherein the conversion includes decoding the visual media file from the bitstream.
 4. The method of claim 1, wherein the specific image item type is associated with a Versatile Video Coding (VVC) standard.
 5. The method of claim 1, wherein the specific image item type is specified as ‘vvs1’.
 6. The method of claim 1, wherein a suggested transition period associated with an image item to be applied for a transition between the image item and a next image item during displaying of the pictures as a slideshow; wherein the suggested transition period is specified as an M-bit unsigned integer value in units of 1/X seconds, where M is equal to 8 and X is a power of 2 and X is greater than 2, and wherein the image item is pointed by an entity ID value which is included in a slideshow entity group, multiple entity ID values of multiple image items in the slideshow entity group are listed in an increasing display order, and the visual media file includes one or multiple slideshow entity groups with different group ID values.
 7. The method of claim 6, wherein the suggested transition period is specified in units of 1/16 seconds.
 8. The method of claim 6, wherein the suggested transition period is further specified for each transition property or each type of transitions.
 9. The method of claim 1, wherein the first syntax element specifies a maximum temporal identification associated with an i-th profile tier level syntax structure, i being in a range of 0 to (a number of profile tier levels−1), and wherein the second syntax element specifies a maximum temporal identification associated with the record of the operating points.
 10. The method of claim 9, wherein the first syntax element is represented as ptl_max_temporal_id[i], and wherein the second syntax element is represented as max_temporal_id.
 11. The method of any of claim 1, wherein the predetermined value is equal to
 0. 12. An apparatus for processing visual media file data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to: perform a conversion between a visual media file and a bitstream, wherein the visual media file comprises image items each comprising a sequence of pictures according to a media file format, and wherein the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format, wherein the media file format specifies that an operating point information (OPI) network abstraction layer (NAL) unit is absent in an image item having a specific image item type or samples of the image item, and wherein the media file format further specifies that, in response to a record of operating points being included in a property descriptor of the operating points that indicates high-level characteristics of the bitstream, at least one of a value of a first syntax element in the record or a value of a second syntax element in the record is constrained to be a predetermined value.
 13. The apparatus of claim 12, wherein the specific image item type is associated with a Versatile Video Coding (VVC) standard.
 14. The apparatus of claim 12, wherein the specific image item type is specified as ‘vvs1’.
 15. The apparatus of claim 12, wherein a suggested transition period associated with an image item to be applied for a transition between the image item and a next image item during displaying of the pictures as a slideshow; wherein the suggested transition period is specified as an M-bit unsigned integer value in units of 1/X seconds, where M is equal to 8 and X is a power of 2 and X is greater than 2, and wherein the image item is pointed by an entity ID value which is included in a slideshow entity group, multiple entity ID values of multiple image items in the slideshow entity group are listed in an increasing display order, and the visual media file includes one or multiple slideshow entity groups with different group ID values.
 16. The apparatus of claim 15, wherein the suggested transition period is specified in units of 1/16 seconds.
 17. The apparatus of claim 15, wherein the suggested transition period is further specified for each transition property or each type of transitions.
 18. A non-transitory computer-readable storage medium storing instructions that cause a processor to: perform a conversion between a visual media file and a bitstream, wherein the visual media file comprises image items each comprising a sequence of pictures according to a media file format, and wherein the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format, wherein the media file format specifies that an operating point information (OPI) network abstraction layer (NAL) unit is absent in an image item having a specific image item type or samples of the image item, and wherein the media file format further specifies that, in response to a record of operating points being included in a property descriptor of the operating points that indicates high-level characteristics of the bitstream, at least one of a value of a first syntax element in the record or a value of a second syntax element in the record is constrained to be a predetermined value.
 19. A non-transitory computer-readable recording medium storing a bitstream comprising image items which is generated by a method performed by a video processing apparatus, wherein the method comprises: generating the bitstream from a visual media file, wherein the visual media file comprises image items each comprising a sequence of pictures according to a media file format, and wherein the bitstream comprises access units each comprising one or more pictures each belonging to a layer according to a video coding format, wherein the media file format specifies that an operating point information (OPI) network abstraction layer (NAL) unit is absent in an image item having a specific image item type or samples of the image item, and wherein the media file format further specifies that, in response to a record of operating points being included in a property descriptor of the operating points that indicates high-level characteristics of the bitstream, at least one of a value of a first syntax element in the record or a value of a second syntax element in the record is constrained to be a predetermined value. 